You don't have to know the ins and outs of how a constant speed unit works or how retractable undercarriage works.
Why would you have to know?
Do you need to know how to calculate volumetric efficiency before you can drive a car? No!
"Complex" is a bit of an overstatement IMHO.
You should expect an hour at most on the ground and, unless you're really hamfisted, 5 hours max in the air.
So many PPLs like to perpetuate the myth that flying is difficult and that all PPL holders are above average IQ. It's not true! (I should know)
Managing your flying however is another story.